1. Field of the Invention
The present invention relates to the field of process control, and in particular, to a knowledge-based method of controlling an injection molding machine production process wherein operating parameters required for the process sequence are input to a data processing unit by an operator and subsequently one or more injection cycles are implemented according to the stored operating parameters.
2. Background Information
In the past, before beginning the first injection cycle of a plastics molding process, an operator of a plastics injection molding machine used an input unit to input respective operating parameters into a data processing unit. The data processing unit furnished all the input masks i.e., screens or windows for data input) available for the injection molding machine on a data viewing device in succession without any provision for the making of a specific selection.
In other words, the prior system does not allow configuration of an injection cycle in advance. Instead, it offers all possible input masks for input data to the user, even if no input has to be made in one of the input masks because, for example, a particular step in the injection cycle, for which input might be necessary, is not implemented. With the expenditure of a great amount of time, respectively required input masks had to be given the necessary parameters.
This process resulted in a high frequency of input errors. For example, during this input, it could not be determined whether all sequential steps of an injection cycle followed one another in an appropriate manner. Further, even if it were desired, certain steps could not be performed several times, such as, for example, repeated opening or closing of a mold closing unit. Moreover, only the respective injection cycle could be input, without consideration of start-up and shut-down phases in a production sequence.
Therefore, the prior art method provided such a poor process overview that the machines could only be set up by expert, trained personnel with the expenditure of substantial amounts of time and effort.
Unexamined Published German Patent Application DE-OS 4,025,221 discloses a method of adjusting an injection molding machine based on empirically or systematically determined values. An optimization program is employed which contains basic knowledge about the rules of injection molding, and a range of characteristics composed of operating parameters.
However, this method is designed to optimize an injection molded object in the course of several injection cycles by adjusting and re-adjusting the machine, that is, the method is for quality control purposes. Therefore, those parameters that concretely influence the injection molded object are input, but not values that only influence the injection cycle itself, such as, for example., mold opening or ejection times. Furthermore, the presence of peripheral devices and material supply are not considered in this method. The operator is able to influence only the computer aided design (CAD) simulated filling of the mold. Thus, this method begins only at a point where components are to be optimized, that is, after initial set up of the machine. This method is unable to contribute to increases in quality at the time when the injection molding machine is initially set up.